Gregoritex's lua callbacks ruin fancyhdr processing

[pietvo]

When you add a multiline header to a document, and the pagebreak is taken when a Gregorio score is active, the Lua callbacks post_linebreak and disable_hyphenation ruin the header (same with footer). So gregoriotex should reset these callbacks during header and footer processing and reinstall them after that. (Only if a score is being processed). Fancyhdr version 4.5 and later have hooks to make this possible.

gregoriotex 2021/03/13 v6.0.0
LuaHBTeX, Version 1.18.0 (TeX Live 2024) (format=lualatex 2024.12.27)

[pietvo]

gregoriotest.pdf
gregoriotest.zip

On the first page the header is cut off and not hyphenated. On the following pages the header is correct, because the page break is outside of the score.